A regional plot for the 1.8 Mb peak of association on chromosome 18 containing the MSTN and NAB1 genes. Association plot of the 1.8 Mb region encompassing 40 SNPs (diamonds) and the Ins227bp polymorphism (circle) ranging from one SNP upstream and one SNP downstream of the seven SNPs significantly associated with optimum racing distance following correction for multiple testing. The y-axes plot -log10(P-values) for each SNP (diamonds) and r2 (blue line) between g.66493737C>T and all other SNPs. The x-axis plots the physical position of each SNP in the region. The best SNP, g.66493737C>T, is indicated with a blue diamond. Each SNP is color coded according to the strength of LD with g.66493737C>T: r2 ≥ 0.8, red; r2 ≥ 0.5 < 0.8, orange; r2 ≥ 0.2 < 0.5, yellow; r2 < 0.2, white.